An IC is a device that includes numerous electronic components (e.g., transistors, resistors, diodes, etc.) that are embedded typically on the same substrate, such as a single piece of semiconductor wafer. These components are connected with one or more layers of wiring to form multiple circuits, such as Boolean gates, memory cells, arithmetic units, controllers, decoders, etc. An IC is often packaged as a single IC chip in one IC package, although some IC chip packages can include multiple pieces of substrate or wafer.
The use of configurable integrated circuits (“ICs”) has dramatically increased in recent years. One example of a configurable IC is a field programmable gate array (“FPGA”). An FPGA is a field programmable IC that often has logic circuits, interconnect circuits, and input/output (I/O) circuits. The logic circuits (also called logic blocks) are typically arranged as an internal array of circuits. These logic circuits are typically connected together through numerous interconnect circuits (also called interconnects). The logic and interconnect circuits are often surrounded by the I/O circuits. Like some other configurable ICs, the logic circuits and interconnect circuits of an FPGA are configurable.
FPGAs have become popular as their configurable logic and interconnect circuits allow the FPGAs to be adaptively configured by system manufacturers for their particular applications. Also, in recent years, several configurable ICs have been suggested that are capable of reconfiguration at runtime. However, there has not been much innovation regarding ICs that can configure one or more times during one clock cycle. Consequently, most reconfigurable ICs take several cycles (e.g., tens, hundreds, or thousands of cycles) to reconfigure.
Recently, there have been configurable ICs that can configure at least once during each clock cycle. Ideally, the configurable IC can configure multiple times during sub-cycles within one clock cycle. See, e.g., the U.S. patent application Ser. No. 10/883,276 entitled “Configurable Circuits, IC's, and Systems”, filed on Jun. 3, 2004, now U.S. Pat. No. 7,109,752. Such configurability would have many advantages, such as enabling an IC to perform numerous functions within any given clock cycle. Such a reconfigurable IC may contain reconfigurable logic circuits that can perform different functions in different sub-cycles. There are also many applications today that require different functions to be performed on the same set of inputs based on a certain condition that is only determined during runtime. There is, therefore, a need in the art to make a reconfigurable IC that can conditionally perform different functions on the same set of input based on a user-design signal.